Fastening circuit boards of electronic devices on a carrier is generally understood in the related art. Often, this carrier is a housing of the electronic device. The attachment is performed using a conventional connecting arrangement, such as e.g. screws, rivets or also electrically conductive adhesive bonds. These connecting arrangements often fulfill not only the mechanical function of holding or fastening, but also an electrical function. Thus, metallic carriers or housings also act as electrical shields against electromagnetic radiation, for shunting static charges or for grounding the housing and at the same time for fixing a ground potential for an electric or electronic circuit situated on the circuit board.
If the circuit board is mechanically fastened on the carrier, then this does not guarantee that the desired electrical connection between the carrier or the housing and the circuit board is also properly established. Once the housing is closed, it is normally no longer possible to determine whether all electrical connections between the housing and circuit boards were correctly established. This may result in failures or malfunctions of the electronic device or in a noncompliance with specified properties such as EMC stability for example. Mechanical vibrations, as occur particularly frequently in devices installed in motor vehicles, may also result in malfunctions, which is particularly critical if the power supply (normally the negative pole of the vehicle electrical system voltage) is connected to the housing.
An objective of the exemplary embodiments and/or exemplary methods of the present invention is therefore to create a device which makes it possible to check a proper attachment of a circuit board on a carrier. This is to be possible even when the carrier is a closed housing. It is also to be possible to perform the check while an electronic device is operated in use, for example in a motor vehicle.
This objective is achieved by the features described herein. Advantageous refinements and developments of the exemplary embodiments and/or exemplary methods of the present invention are disclosed by the further descriptions herein.
One aspect of the exemplary embodiments and/or exemplary methods of the present invention is to include electrically conductive connecting arrangement in an electric circuit. This electric circuit is closed when the connecting arrangement have established a proper electrical connection between the circuit board and the carrier. The connecting arrangement thus act as an electrical switch for the electric circuit thus established. This electric circuit may be checked by an evaluation device, for example by measuring the resistance value of the electric circuit. This evaluation device may be used in the final testing in production. It may also be accommodated, however, as an evaluation circuit on the circuit board itself and thus perform the check continuously in operation. With respect to the exemplary embodiments and/or exemplary methods of the present invention one may assume that when there is a proper electrical connection between the circuit board and the carrier, the mechanical attachment is properly established as well. For checking several connecting points between the circuit board and the carrier, the exemplary embodiments and/or exemplary methods of the present invention provides two basic variants, namely, on the one hand, a serial circuit and, on the other hand, a parallel circuit of all connecting points to be monitored in the electric circuit.
The exemplary embodiments and/or exemplary methods of the present invention is also applicable if the carrier is made of electrically nonconductive material, in which case the mentioned serial circuit is practical. In this case, two adjacent contact surfaces may be provided per attachment point on the circuit board, which are bridged by the electrically conductive connecting arrangement.
The exemplary embodiments and/or exemplary methods of the present invention is explained in greater detail below on the basis of exemplary embodiments in connection with the drawing.